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Analysis of acid‐stressed Bacillus cereus reveals a major oxidative response and inactivation‐associated radical formation
Author(s) -
Mols Maarten,
Van Kranenburg Richard,
Van Melis Clint C. J.,
Moezelaar Roy,
Abee Tjakko
Publication year - 2010
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2009.02132.x
Subject(s) - bacillus cereus , oxidative stress , cereus , biology , peroxynitrite , superoxide dismutase , biochemistry , microbiology and biotechnology , flow cytometry , bacteria , food science , superoxide , enzyme , genetics
Summary Acid stress resistance of the food‐borne human pathogen Bacillus cereus may contribute to its survival in acidic environments, such as encountered in soil, food and the human gastrointestinal tract. The acid stress responses of B. cereus strains ATCC 14579 and ATCC 10987 were analysed in aerobically grown cultures acidified to pH values ranging from pH 5.4 to pH 4.4 with HCl. Comparative phenotype and transcriptome analyses revealed three acid stress‐induced responses in this pH range: growth rate reduction, growth arrest and loss of viability. These physiological responses showed to be associated with metabolic shifts and the induction of general stress response mechanisms with a major oxidative component, including upregulation of catalases and superoxide dismutases. Flow cytometry analysis in combination with the hydroxyl (OH·) and peroxynitrite (ONOO ‐ )‐specific fluorescent probe 3′‐(p‐hydroxyphenyl) fluorescein (HPF) showed excessive radicals to be formed in both B. cereus strains in bactericidal conditions only. Our study shows that radicals can indicate acid‐induced malfunctioning of cellular processes that lead to cell death.